The invention relates to a frame member for a belt retractor and a method of manufacturing a substantially plate-shaped frame member of a belt retractor.
A belt retractor typically includes a belt reel to which webbing that can be reeled up and unreeled from the belt reel is fastened. The belt reel is supported on the frame members of the belt retractor. In the case of crash webbing is to be prevented from being unreeled from the belt reel. For this purpose, a locking mechanism is usually provided which may comprise a ratchet arranged on the belt reel as well as locking teeth formed on the frame member. The ratchet is controlled in a vehicle and/or webbing sensitive manner within the locking teeth so that the belt reel is blocked and the webbing is not allowed to unreel any further. The ratchet may engage due to its inertia. Instead of the ratchet, the belt reel may also include counter teeth interacting with the locking teeth on the frame member. The belt reel is displaced by reason of the forces occurring so that the teeth enter into mutual engagement and the belt reel is blocked.
Upon locking the belt reel high forces will occur between the locking teeth on the frame member and the counter teeth or the ratchet, said forces entailing high load in the form of a high surface pressure on the corresponding contact faces. The surface pressure is dependent on the force occurring and the available contact face and significantly determines the selection of the materials used for the respective component parts. The component parts used in the belt retractor are made of materials having an as low density as possible, while the component parts still have to resist the surface pressures to be expected.